This invention relates to an improved extruder and more particularly to a new and improved extruder screw for plasticizing plastic materials such as polyurethanes.
The mixing and working of plasticizing materials with extruder screws have been directed to increasing their efficiency by improving the overall efficiency of the screw design for general purpose work. The design changes have been generally in the flight configuration or pitch design. To increase the working of the plastic material, improvements have been directed to leading off the fluent material as well as to providing a series of mixing pins to provide a more thorough mixing. The present invention is directed to providing a novel means for increasing shear while simultaneously increasing heat transfer and altering the flow pattern to enhance mixing and to reduce temperature fluctuation across the screw channel which improves the quality and quantity of the mixed product.